Procedure and apparatus for use in vulcanizing hollow shaped articles



' Oct. 14, 1947. H. P. SCHRANK I I r 2,428,944

PROCEDURE AND APPARATUS I OR USE IN VULCANIZING HOLLOW SHAPED ARTICL ESFiled July '15, 1942 YINVENTOR: Harry P. Schmnk ATTORNEY Patented Oct.14, 1947 PROCEDURE ,AND AIfPARATUS FOR USE IN, VULCANIZING Ho LoW;SHAPED AarIcLEs.

Harry R. Schrank, Munroe Falls, Ohio, assignor to Seiberli g Ru r ompny, Barberton,

b e. weenie? of Delaware ep i ae w 1. 1942, eri p, 50 96 ,7 ims- This,invention relates to procedure and apparatus for use in vulcanizinghollow shaped articles of rubber, rubberized fabric or the like.

Hollow inflatable articles of rubber, rubberized fabric or the like andfabricated with one or more spliced or lapped joints, as isthe case withinflatable boats and floats are preferably vulcanized under the directheat and pressure of steam or like vulcaniz'ing fluid; so asthoroughlyto weld the spliced or lapped joints,

During the initial stages of the vulcanization the rubber softens andtends to flow, hence prior attempts to vulcanize such articles have notbeen entirely satisfactory, due to the production of articles of thiskindwith leaky vulcanized joints. This has been due either to stretchingor wrinkling or buckling of the spliced or lapped jointsd epending uponwhether the articles are over or under inflated during the cure. v

It has been found that the successful vulcanization of such articlesunder the direct action of steam depends upon controlling thedifferential in pressure between the inside and outside of the article,this differential being slightly higher, say one-half ounce per squareinchon the inside of the article, to hold-it in the correct inflatedshape in which it is to be vulcanized without folds or wrinkles, butbeing insufficient to stretch the article to spread or open'the laps;scams or splices when the rubber softens during initial stages ofvulcanization.

The articlesmay be pre inflated andintrodueed into the vulcanizer orheater, but it will be ape parent that due to variationsin heat andpressure I as the pre-inflated articles are subjected to the curingfluid, the differential in pressure at all times must be accuratelycontrolled, otherwise the article may be unduly stretched by internalpressure or collapsed or wrinkled by excessive external pressure. p 5 iIn accordancelwith the procedure of the present invention the fabricatedarticle may be first in flatedsufliciently to distendfit to its normalshape without excessive stretching, and then mea iis are so associatedwith the articlefasto be responsive to pressure differential or thechange in shape of the article under the pressures of the fluids actingon them, to vary the pressure (as for example of the inflatin medium) inaccordance with changes in pressure difierential or the shape of thehollow article whereby to maintain the pressure differentialsubstantially constant at all times while the article is being cured.

. The present invention has, therefore, the obkct of providing andadapting such procedure t0 vnlcamzatio-n of hollow inflatable articlesofv rubber, rubberized fabric or the like, and also to provide suitableapparatus 'for carrying out such procedure:

' Another object of the invention is to provide and'adapt similarprocedure and apparatus, for use in vulcanizing or curing hollowarticles of rub ber 01' the like, whether such articles are flexible andinflatable or are of rigid construction.

The invention'may be embodied and carried out in the apparatusillustratedin the accompanying drawings and described below, but it i tobe understood that the invention is not limited to the specific formthereof illustrated and described. 15

Of the accompanying drawings;

Figure 1 is a sectional elevation through a vulcanizer or heater inwhich the. improved apparatus is embodied and shown in use for.vulcanizing an article such as an inflatable float of rubberized fabric,and V Figure 2 is a diagrammatic view ofthe pressure differentialcontrol device and associated piping.

Referring to the drawings, the numeral Ill designates what is usuallyreferred to in the art as an open heater into which a truck or dolly I Imay be run on rails l2, l2'and may support thereon a, hollow inflatablefloat or boat iii, in cluding one or more cells or compartments.

Associated with the dolly l l is a manifold M from which one or morefluid supply connectors l5 may be extended to the one or more inflationvalves IE on each compartment or cell of the article. 'Mans' forsupplying a fluid pressure medium around the article is shown at H. Onthis manifold [4 there preferably is a pressure gauge It which maybearranged on'the outside of the heater. 4 A

A fluid pressure supply line I9 is also connected to manifold M and onthis line is a supply branch l9? and a pressure relief branch I9 Thesebranches may be extended to'the outside of the heater as shown." Thebranch l is controlled by a supply valve, 2i} andv the branch [Why asimilar valv'efZ l arranged to exhaust the inflatingmeolium from supplyline l9. Valves Zfi'and 2] may be of a known type includingspringepressed s'l'fin l'sffll and 2| respectively, arranged to bedepressed to open the valves.

In the particular embodiment of the invention shown, these valves areassociated with an element 22 comprising a lever pivoted at 23 on abracket 24 mounted on the dolly H, and having depending from its freeend a follower 24 arranged to rest on the inflatable article I 3,whereby the lever 2.2 will be responsive to change in shape of thearticle 13 being raised when the article tends to become excessivelyinflated by internal pressure and being lowered when the article tendsto become excessively compressed and collapsed by external pressure, theweight of the lever and follower being sufficient to cause it to ride onthe surface of the article l3 at all times.

Lever 22 is shown arranged between valves 20 and 2! which are arrangedwith their operating stems 20 and 21 to be engaged and depressed bylever 22 as it moves in one direction r the other. There may be a slightclearance between the lever 22 and valve stem 213 and 2M when the partsare in a position representing normal pressure differential conditions(as illustrated), the valves being so set as to be normally closed tomaintain normal differential pressure conditions when not operated bylever 22.

If the inflation pressure should fall (with respect to externalpressure) then the weight of the lever 22 and follower 24 causes it tolower and this weight i sufilcient to overcome the valve spring (notshown) on stem 20 and to open the inflation pressure supply valve 20,valve 2| being, of course, maintained closed by its spring-pressed stem21 The same result would occur if the external pressure should rise withrespect to the internal or inflation pressure.

If the inflation pressure should rise (with respect to externalpressure) to exceed the determinate differential, lever 22 will be swungupwardly depressing stem 2P into its valve 2! and opening said valverelieving the internal pressure. Valve 20, of course, will be in closedcondition at this time. The pressure will thus be relieved until thedesired differential is attained Whereupon lever 22 will lower to itsnormal position shown. The same result will occur, as will beunderstood, should the external pressure fall with respect to theinternal pressure.

It will be obvious that the invention may be embodied in many differentforms with elements having Various physical or mechanicalcharacteristics so as to be responsive to pressure differential andoperable to actuate the inflation and relief valves of one medium or theother, that is, of either the inflation pressure or the externalpressure. The particularform of the invention shown is merely thesimplest and best way of accomplishing the purpose.

vulcanization of flexible or rigid articles of rubber under internal andexternal pressures may be controlled by use of an inflatable envelop offlexible material separate from the article bein vulcanized, the changeof shape of which under differential pressure acting in the heater maycontrol the differential pressure acting on the separate article beingcured. In fact one compartment of a multi-compartment boat or float I3similarly serves to control differential pressure in all thecompartments including the sepa rate compartment 30 when a singlecontrol device, such as follower 24 as shown, is associated with thefloat or boat on said compartment I3.

What is claimed is:

1. That method for vulcanizlng or curing hollow articles of rubber orthe like under internal and external fluid pressures which comprisessupplying fluid mediums under pressure internally and externally of sucharticles, associating with said article an inflatable envelop offlexible material and subjecting it to said internal and externalpressures, and varying the pressure of one of said fluid mediums inaccordance with changes in shape of said envelop under varying pressuredifferentials so as to maintain the pressure of a fluid medium.

sure differential in the hollow articles substantially constant.

2. Apparatus for vulcanizing or curing hollow articles of rubber or thelike under internal and external fluid pressures which comprises meansfor supplying fluid mediums under pressure internally and externally ofsaid articles, means comprising a flexible inflatable envelop associatedwith said supplying means to be subjected to said internal and externalpressures, and means controlled by change in shape of said envelop undervarying pressure differentials for maintaining the pressure differentialin said articles substantially constant.

3. Apparatus for vulcanizing or curing hollow articles of rubber or thelike under internal and external fluid pressures which comprises meansfor supplying fluid mediums under pressure internally and externally ofsaid articles, means comprising a flexible inflatable envelop associatedwith said supplying means to be subjected to said internal and externalpressures, and means c011- trolled by change in shape of said envelopunder varying pressure differentials for maintaining the pressuredifferential in said articles substantially constant, said meanscomprising a follower engaged with said envelop.

4. Apparatus for vulcanizing or curing hollow articles of rubber or thelike under internal and external fluid pressures which comprises meansfor supplying fluid mediums under pressure internally and externally ofsaid articles, means comprising a flexible inflatable envelop associatedwith said supplying means to be subjected to said internal and externalpressures, and means controlled by change in shape of said envelop undervarying pressure differentials for maintaining the pressure differentialin said articles substantially constant, said means including a followerengaged with said envelop and control valves actuated by said followerto supply and release pres- HARRY P. SCHRANK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS 1,671,275 Clithero May 29, 1923

